In 1991, Psion launched their first clamshell format organiser, the
Series 3. It featured a NEC V30H 8086-compatible processor running at
3.84MHz. The machine featured 128K or 256K of RAM, and into its 384K
ROM Psion fit their EPOC operating system (as used in the MC 200 & 400
models, upgraded with new features), several good office/PDA
applications and the OPL programming language.

In 1993 the Series 3a was launched. Despite the insignificant change
in version number, this was a major upgrade: 256K or 512K RAM, double
the processor speed, a much bigger LCD screen and upgraded sound
capable of playing back digital samples at 8-bit or 13-bit quality.
The 1MB ROM included new applications: a spreadsheet and a much
upgraded Agenda package comparable to agenda/diary applications on
desktop machines. 1MB and 2MB models were added later, and included a
Patience game.

The Series 3 range of computers continued to be developed until 1998,
when the model 3mx was released. This model was discontinued in 1999.
Much of their software was ported to the Series 5 range, which was
produced between 1997 and 2001, and some of the software, especially
the built-in programming language OPL, is still being used and
developed in Symbian mobile phones (Series 60, etc.), which are the
descendants of the Psion PDA software architecture.

Thanks to Damian Walker for the information, Jonathan Barnes for the picture.